Cita APA (7th ed.)
Poonia, M., & Sharma, S. (2017). Environmental studies. Khanna Book Publishing Co.
Cita Chicago (17th ed.)
Poonia, M.P, i S.C Sharma. Environmental Studies. New Delhi: Khanna Book Publishing Co, 2017.
Cita MLA (9th ed.)
Poonia, M.P, i S.C Sharma. Environmental Studies. Khanna Book Publishing Co, 2017.
Atenció: Aquestes cites poden no estar 100% correctes.